Tuning the chemical environment of palladium bimetallic nanocatalysts via C3N4 support engineering and bimetallic synergy for boosted visible-light-driven hydrogen evolution from formic acid

Abstract

Hydrogen (H₂) production via visible-light-driven formic acid (HCOOH) dehydrogenation is a sustainable pathway, yet its efficiency is bottlenecked by the lack of catalysts with rationally tailored active sites. Herein, we propose a synergistic regulation strategy to optimize the chemical environment of palladium (Pd)-based bimetallic nanocatalysts—integrating three core approaches (bimetallic composition tuning, C₃N₄ support engineering, and visible-light utilization)—for efficient visible-light-assisted H₂ evolution from HCOOH. We synthesized a series of Pd-based bimetallic nanoparticles (NPs) supported on C₃N₄-derived materials (CNU, CNUM, etc.) and evaluated their catalytic performance. Comprehensive characterization confirmed well-defined structures: Pd-based alloy NPs (e.g., ∼2.2 nm PdNi/CNU) achieved uniform dispersion via anchoring by C₃N₄'s surface –OH groups, with modulated Pd electronic states and enhanced visible-light harvesting. Among the catalysts, PdNi/CNU exhibited the highest activity: its turnover frequency (TOF) reached 504.2 h⁻¹—18.61 times that of PdMo/CNU (27.1 h⁻¹)—and further increased to 751.8 h⁻¹ with visible-light assistance at 298 K. Trapping experiments identified holes (h⁺) and electrons (e⁻) as key active species, and a protonation mechanism was validated. This work highlights that synergistic optimization of the chemical environment of Pd-based bimetallic NPs is an effective strategy for developing high-performance HCOOH dehydrogenation catalysts, providing valuable guidance for sustainable H₂ production.